Magnetic fields have measurable characteristics. Some materials and devices when placed is a magnetic field will cause changes in one or more of the measurable characteristics. Consequently, the art has developed a number of detection devices that rely upon changes in magnetic fields that occur when a material is placed in the magnetic field to reveal something about that material. Some industries, particularly semiconductor manufacturers, test products for defects by observing what happens when the semiconductor material is exposed to a magnetic field. Such testing is often done by using electron paramagnetic resonance (EPR) spectrometers. Conventional EPR spectrometers range in cost from several hundred thousand dollars to about one million dollars for state of the art systems. Considerably less sensitive and much less versatile systems can be purchased for as little as $25,000. Electrically detected magnetic resonance (EDMR) spectrometers can be built with modest modification to an EPR spectrometer and can offer multiple advantages over these systems in applications of defect detection in solid state electronics. They offer much higher sensitivity and a sensitivity limited exclusively to imperfections which play a role in the electronic behavior of the devices under study. But, the inexpensive EPR spectrometers would be very difficult to modify for EDMR. The space and power requirements for the more expensive EPR spectrometers are considerable, with typical systems utilizing power supplies of several kilowatts and chilled water heat exchangers and requiring footprints of ten or more square feet.
Although conventional EPR and EDMR spectrometers are quite powerful analytical tools for the evaluation of materials physics problems in solid-state electronic devices, the measurements are quite time consuming and generally require extensive sample preparation to allow for insertion of samples into specialized microwave resonant cavities. There is a need for a much less expensive and convenient scheme for EDMR evaluation of semiconducting device technology. Additionally, conventional EDMR measurements require very large magnetic fields (typically 0.35 Tesla or higher) which must be exceptionally stable and high frequency electromagnetic radiation (typically 9 GHz or higher). There is a need for a measurement device that can determine the magnitude of a static magnetic field and detect changes in a magnetic field without the need for the large magnetic field. A detection device that does not need a high field and microwave resonator would be considerably less expensive and permit far more straightforward measurements. Indeed, there is a need for a detection device that consumes less energy and has a smaller footprint than available EPR spectrometers and yet can be used for testing and in other applications where conventional EPR spectrometers are used.